Mag Starter help. Tree Mill
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  1. #1
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    Default Mag Starter help. Tree Mill

    Wiring diagram for tree mill, 2UVR-C

    https://drive.google.com/open?id=12j...mrepb9yzLimgbk

    I have real 3 phase power. Both Feed Motor and Head Motor are somehow mis-wired. Both run fine, but I cannot turn them on-off with the switches. Start-stop switches have been checked and work properly. I have tried all 6 possible combinations of hooking 3 wires to 3 terminals. In ALL cases both motors run when main power is turned on. In two of the configurations a push of the momentary OFF switch stops the motor but it restarts when released.
    I am thinking that there is a bad connection somewhere in the contactor and not in the ON/OFF system.
    Below are some of the voltage readings:

    L1-L2 240V L1-Ground 218V 2-Ground 0V
    L1-L3 240V L2-Ground 121V 3-Ground 120V
    L2-L3 240V L3-Ground 120V 2-3 0V

    L1-2 0V L1-3 248V
    L2-2 0V L2-3 242V
    L3-2 0V L3-3 0V

    Any help would be greatly appreciated. Otherwise I am running the mill by wearing out the main power strip.

    Ivan Vegvary
    Sandy, Oregon

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    The problem is not the L1, L2, L3 connections. You need to look at terminals 2 and 3. This is a classic latching relay setup.

    Power comes from L1, through the "stop" switch which is normally closed, to terminal 2. When the "start" switch is pushed, it momentarily provides power from terminal 2 to terminal 3. That energizes the magnet in the contactor and closes a contact between 2 and 3. At that point, you can let go of "start" and the motor will keep running.

    When you press "stop", power to terminal 2 is interrupted and the coil is no longer energized. That allows the contactor to open and it opens the contact between 2 and 3.

    If you make the wiring like the diagram you posted, it will work correctly. You should be able to find the fault with a simple volt meter.

    From your description, it seems that maybe the "start" button is not working correctly. Perhaps it is stuck closed.

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    The diagram you marked up is really a connection diagram for a A-B starter.

    Should be wired this way.

    A wire from L1 (line side of contactor) to stop sw. A jumper from second term of stop sw to start switch. A wire from that junction to one side of the aux contact on the front of the starter labeled 2. A wire from the second term of the start sw to the second term of the aux contact labeled 3. A jumper wire from aux cont 3 to one side of the coil. A wire from the second term of the coil to to one of the overload relays. A jumper wire from the sec term of the OL to a term on the second OL relay. A jumper wire from the sec term of the OL to L2 line side of the starter. Both OL relay contacts should be closed. The start contact is a normally open contact, the stop contact is normally closed.

    This is how the circuit works.

    Power from L1 goes through the N/C contact (stop), then to the N/O contact (start). When the start contact is pressed, current goes through through the coil through the closed OL relay contacts and back to L2 line side. The coil operates closing the main contacts and sending power to the motor. N/O aux contact on the front of the starter closes and provides an alternate path around the N/O start contact so that when the start contact is released, there is still power to the coil through the aux contact. Pressing the stop contact releases the coil, the aux contact opens and the circuit shuts down. Similarly, either on of the OL opening will do the same thing.

    Tom

    Edit Ewlsey has a faster keyboard.

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    Thank you Ewlsey and Tom,
    Still cannot get it to work. With both ON/OFF buttons of wiring removed I still read 120 Volts on 3 to Ground. Should this be so? Is this my problem?
    Thank you so much.

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    Meant to say, buttons AND wiring remove. Still 120 volts on terminal 3.

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    Are the switches mounted on the starter like this?

    https://www.ebay.com/p/Allen-Bradley...d=254215146703

    Momentary switches will have to use an auxiliary contact on you starter. That would be 2 and 3. The stop switch breaks it's NC connection and disrupts power to the starter coil. The only thing it would be is the switch or the connections to it. Very easy to fix.

    A picture of your stuff?

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    Quote Originally Posted by Ivan Vegvary View Post
    Thank you Ewlsey and Tom,
    Still cannot get it to work. With both ON/OFF buttons of wiring removed I still read 120 Volts on 3 to Ground. Should this be so? Is this my problem?
    Thank you so much.
    Be careful that you are not reading "ghost voltage" or induced voltage in the coil. AC power tends to be induced in adjacent circuits. It will show voltage on the meter, but in reality is has no current carrying capacity. You can rig up a test light with a incandescent light bulb. That might avoid some confusion.

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    Is it possible the line contacts are stuck together? Disconnect power and check control switches with ohm meter. I don't see the point of checking voltage to ground. You could disconnect the coil wire opposite the switches and then check volts from that wire to all the switches starting with the first and moving toward coil. Since motor runs all the time control circuit is miswired or one of the switches is sticking closed.

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    SOLVED !!
    Prior to this problem I had noticed that there is a blown large tubular fuse. Said fuse was coming from the separately attached transformer that is supposed to convert the high voltage down to 120V feeding the attached outlet box. I replaced the fuse and all my troubles began.
    REMOVED THE FUSE
    Evidently the wiring leaving the fuse (haven't full traced it) was feeding the contactor in some way, providing current. With fuse removed all systems work.
    Thank you all for your kind words and suggestions. Wiring up per suggestions and diagram, makes all systems go.

    Thank you!!

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    You're not done yet. You need to find out what's going on with the fuse. I smell an aw shit ready to happen.

    Tom

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